Boiler



T. C. ERVIN BOILER Filed May 12, 1936 Patented June 29, 1937 STATES PATENT EEQE BOILER This invention relates to steam boilers.

Special objects of the invention are to eliminate the undesirable features resulting from mud ring constructions heretofore employed, to attain a more effective heat transfer and better circulation, to avoid the need for staybolts or rivets about the lower rim of the firebox and hence avoid the leaks commonly resulting from such staybolts, and to accomplish these and other desirable objects in a simple, economical and entirely practical structure.

These objects are attained by the novel features of construction, combinations and relations of parts hereinafter described, illustrated in the accompanying drawing and broadly covered in the claims.

The drawing accompanying and forming part of the specification illustrates practical embodiments of the invention, but it will be under- 0 stood that it may be further modified and changed .all within the true intent and broad scope of the invention. 1

Fig. 1 is a side elevation, broken and partly in section of an oil field boiler incorporating features of the invention.

Fig. 2 is an enlarged broken sectional detail on substantially the plane of line 22 of Fig. 1.

Fig. 3 is a broken horizontal sectional detail on substantially the plane of line 33 of Fig. 1.

Fig. 4 is a view similar to Fig. 2 illustrating a modification.

Fig. 5 is a broken sectional view of the smoke box and feed water heater construction.

Fig. 6 is a sectional view of the latter as on substantially the plane of line S6 of Fig. 5.

One of the important features of the present invention is that the usual mud ring construction is eliminated and that the outer and inner sheets forming the firebox are brought together and welded around the bottom of the firebox.

This is accomplished in the illustration by forming the back head i, with an inwardly directed flange 8, at its lower edge, the wagon top 9, with inwardly directed flanges ll], along its lower edges, the throat sheet H, with an inwardly extending flange 12, at its lower edge, the firebox door head 23, with an outwardly extending flange Hi, at its lower edge, the firebox sheet l5, with outwardly extending flanges It, at the lower edges and the firebox head ll, with an outwardly bent flange 58, at the lower edge and by integrally connecting such opposed inwardly and outwardly directed bottom flanges with a substantial welded joint.

In the first form of the invention illustrated Chattanooga, Tenn.

1936, Serial No. 79,318

in Figs. 1, 2 and 3, this integral joint is effected through the medium of an interposed relatively narrow welding ring 89, to the opposite sides of which the flanges of the outer and inner firebox forming sheets are welded at 20, 2i.

In a modified form of the invention, the bottom flanges of the side sheets are directly welded together as indicated at 22 in Fig. 4.

' In addition to the usual staybolts 23, connecting the outer and inner sheets, a special row of staybolts 24, is placed an allowable pitch above the inside Welded together edges of the plates for carrying the stresses occasioned by the boiler pressure.

The narrow welding ring, when employed, may be flushed with the sheet flanges at the inside and the outside of the water leg or may project slightly as illustrated, the projection at the outside then serving as a reinforcement to take any load at the bottom of the firebox.

This construction has all the advantages of both the wet or closed bottom type of firebox with a mud drum under the bottom of the firebox and the dry or open bottom type with a solid mud ring and without the disadvantages as to the restricted bottom opening in the wet type or the disadvantages of unequal expansion and possible leaks present with the dry bottom, mud ring form of construction. The flanging of the lower edges of the boiler sheets in opposite directions stiffens and strengthens these members and keeps the side and bottom walls substantially the same thickness, maintaining heating and expansion and contracting conditions substantially uniform.

The fire tubes are shown at 25, extending from the firebox head 15, to the front tube sheet 26. Forward of this tube sheet, there is indicated a smoke box 21, closed by the front smoke door 28, and the surrounding boiler shell 29, and this smoke box is shown as having the usual stack 30.

Within the smoke box, a feed water coil 3|, is located, preferably or usually in a single layer coil substantially conforming to the internal dimensions of the boiler shell. This coil has an external inlet 32, at one side of the smoke box and an external outlet 33, at the opposite side, the latter usually being connected into the forward end of a boiler space through a check and globe valve. The convolutions of this feed water heating coil are shown as separated at the top at 34, so as not to impede the stack draft. Thus without interfering with the flow of combustion products and without adding to the bulk of the boiler, preheating of the feed water is accomplished without abstracting heat which could be utilized in producing steam.

By bringing the firebox sheets together without using a mud ring greater heating surface is provided, better circulation is efiected, a more rapid transfer of heat is accomplished, expansion leaks are avoided and the burning out and leaking of rivets is done away with. Where the wagon top is curved in at its front and back edges to meet the curvature of the throat sheet and back head, it may be welded to the inturned flanges of such sheets, substantially as indicated at 2%, Figs. 1 and 3.

With this new construction, the water is brought closer to the fire, so there is less possibility of burning the sheets and there are no rivets or staybolts to burn out as in the prior socalled wet and dry or open bottom types of boilers. The solid mud ring heretofore employed in the open bottom firebox boilers interfered with expansion and caused leaks, where the present invention entirely obviates such problems. Also, there is a substantially uniform thickness of wall with no overlapped sheets.

What is claimed is:

l. A boiler firebox, comprising spaced outer and inner firebox forming sheets, the outer sheets having their lower edges turned inwardly and the inner sheets having their lower edges turned outwardly and welded connecting means integrally uniting said inwardly and outwardly directed lower edges of said outer and inner firebox forming sheets and including a narrow welding ring to which said outwardly and inwardly directed edges are welded, the lower edges of said welding ring being exposed as a narrow edge reinforcement between the bent lower edge portions of said firebox forming sheets.

2. A boiler firebox, comprising spaced outer and inner firebox forming sheets, the outer sheets having their lower edges turned inwardly and the inner sheets having their lower edges turned outwardly and welded connecting means integrally uniting said inwardly and outwardly directed lower edges of said outer and inner firebox forming sheets, said outer firebox forming sheets comprising a back head, wagon top and throat sheet all having inwardly directed lower edges and said inner firebox forming sheets comprising a firebox door sheet, a firebox tube sheet and a firebox sheet all having outwardly directed lower edges, said firebox door sheet having inwardly extending side flanges forming the rearward corners of the firebox space and said inwardly extending side flanges also having outwardly turned lower edges and secured by said welded connecting means to both the wagon top and the back head.

3. A boiler firebox, comprising spaced outer and inner firebox forming sheets, the outer sheets having their lower edges turned inwardly and the inner sheets having their lower edges turned outwardly and welded connecting means integrally uniting said inwardly and outwardly directed lower edges'of said outer and inner firebox forming sheets, said outer firebox forming sheets comprising a back head, wagon top and throat sheet all having inwardly directed lower edges and said inner firebox forming sheets comprising a firebox door sheet, a firebox tube sheet and a firebox sheet all having outwardly directed lower edges, said firebox door sheet having inwardly extending side flanges forming the rearward cornersof the firebox space and said inwardly extending side flanges also having outwardly turned lower edges and secured by said welded connecting means to both the wagon top and the back head, said inwardly and outwardly directed lower edges forming opposed cooperating welding flanges meeting at the lower corners of the firebox to brace and strengthen the same and a row of staybolts connecting the outer and inner firebox forming sheets above the opposed connected flanges and drawing said connected flanges together and carrying the stresses developed by pressure in the boiler.

THOMAS C. ERVIN. 

